The present invention is directed to the field of flanges connected to pipes, and more particularly to a technique for welding pipes, especially manifold pipes to a flange.
In preparing exhaust manifolds and other gas carrying pipes in internal combustion engines, it is usually necessary to provide at least one end of such pipes with a flange which is adapted to be connected to a structure such as an engine head.
More specifically, an exhaust manifold, for example, is usually provided with a common flange connected to the ends of the exhaust pipes or tubes to thereby facilitate the connection of the tubes to the engine head. Typically, in preparing an exhaust manifold, it has been the practice to weld the manifold tubes to the flanges on the "tube side" of the flange, as opposed to the "head side" of the flange, since welding at the latter location would produce a rough surface and a significant amount of the weld material would project into the exhaust port, thus restricting the flow passages.
Unfortunately, welding the manifold to the flange from the tube side is made difficult by the arrangement of the tubes in the manifold. Specifically, it is necessary to provide a weld about the entire circumference of each tube. Since there are usually a number of tubes which extend from the engine head to the manifold collector, adjacent tubes interfere with each other during welding. The welding about the entire circumference of each tube from the tube side is thus rendered relatively difficult, expensive and time consuming. Also, an undesireable gap between the tube and the flange, on the head side of the flange, will result when this technique is employed.